HDD important issue

With the Western Digital hard drive (not SSD), there is an important issue: using the APM (Advanced Power Management) there are too nomerous spin-down, that can damage the hard drive. To confirm this issue you have to install smartmontools:

# pacman -S smartmontools

And you have to run multiple times this command (once in a minute for like 5 minutes):

# smartctl -a /dev/sda|grep Load_Cycle_Count

If the number under Load_Cycle_Count is increasing in a small amount of time (1 or 2 in a minute) you have this issue.
The problem is easily solvable using laptop-mode-tools. In your /etc/laptop-mode/laptop-mode.conf you have to set:

This disable all power management systems of the hard drive cause a light heat up (maybe). The same behaviour can be obtained running this command:

# hdparm -B 255 /dev/sda

the 255 number is the power-management level, in a range of 1-255 where 1 is maximum powersaving and 255 powersaving disabled. However setting the value to 253 causes a lot of spin-down. Setting the spin-down feature (it parks the heads away from disk) however can save hdd in case of fall.

If you are using linux drivers for wifi you should also edit the WIFI_DRIVERS array:

WIFI_DRIVERS=("r8192se_pci")

Otherwise the wifi toggle button won't work.

Afterward, you must restart acipd:

/etc/rc.d/acpid restart

Power Management with Laptop Mode Tools

You can use Laptop Mode to substantially increase your battery life on Linux. To do so, Install the [Laptop Mode Tools|laptop-mode-tools] from extra repo:

pacman -S laptop-mode-tools

and add "laptop-mode" to your DAEMONS array in rc.conf.
Many of the power managment settings in laptop-mode are disbaled by default, so it is encouraged that you explore the configuration files throroughly. Here are some highlights of configuration options worth exploring:

Super Hybrid Engine

Super Hybrid Engine is a simple FSB tweaker that can radically reduce power consumption.

To enable automatic SHE manipulation just edit /etc/laptop-mode/conf.d/eee-superhe.conf:

CONTROL_SUPERHE=1

If you've configured function keys using acpi-eeepc-generic, you can manually change SHE mode by using Fn+Space.

Wifi Power Management

The linux native wifi driver supports wifi power management. If you are using the linux-native wifi driver, you can enable basic power management by editing /etc/laptop-mode/conf.d/wireless-power.conf:

CONTROL_WIRELESS_POWER_SAVING=1

Suspend2RAM

Install pm-utils:

pacman -S pm-utils

If you are using linux wifi driver you need to unload it before suspending otherwise the machine won't resume. To do this automatically uncomment and edit appropriate line in /etc/pm/config.d/config file:

SUSPEND_MODULES="ehci_hcd r8192se_pci"

The ehci_hcd module is responsible for usb hub. Removing it solves the immediate resume issue (see Troubleshooting)
You can try out the suspend2ram either by using function key Fn+F1 (if you've configured them to use pm-utils in /etc/conf.d/acpi-eeepc-generic.conf) or by running: